Information-governing dynamics of attacker–defender interactions in youth rugby union     

Pedro Passos  Duarte Araújo  Keith Davids  Luis Gouveia  João Milho  SidóNio Serpa 《Journal of sports sciences》2013,31(13):1421-1429

Abstract

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker–defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker–defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m · s^?1, a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker–defender dyads in rugby union over time as spatial proximity to the try line increased.  相似文献   

Improvement of cellular health indicators and muscle quality in older women with different resistance training volumes     

Paolo M. Cunha  Crisieli M. Tomeleri  Matheus A. do Nascimento  João Pedro Nunes  Melissa Antunes  Hellen C. G. Nabuco 《Journal of sports sciences》2013,31(24):2843-2848

ABSTRACT

The main purpose of this study was to compare the effects of resistance training (RT) performed with different training volumes on phase angle (PhA), body water components, and muscle quality (MQ) in untrained older adult women. A second purpose was to assess the relationship between PhA and MQ. Sixty-two older adult women (68.6 ± 5.0 years, 65.2 ± 13.3 kg, 156.1 ± 6.2 cm) were randomly assigned into one of the three groups: two training groups performed either 1 set (G1S) or 3 sets (G3S), or a control group (CG). Body water components and PhA were estimated by bioelectrical impedance (BIA). MQ was determined by dividing skeletal muscle mass estimated by dual-energy absorptiometry (DXA) by total muscle strength from three exercises. After the intervention period, both training groups demonstrated improvements (P < 0.05) when compared with CON for intracellular water, total body water, PhA, and MQ. These results suggest that RT can improve PhA, body water components, and MQ after 12 weeks of RT in untrained older women, regardless of training volume. Furthermore, changes in MQ were positively correlated with changes in PhA (r = 0.60, P < 0.01).  相似文献   

Reliability and validity of different methods of estimating the one-repetition maximum during the free-weight prone bench pull exercise     

Amador García-Ramos  Paola Barboza-González  David Ulloa-Díaz  Angela Rodriguez-Perea  Darío Martinez-Garcia  Francisco Guede-Rojas 《Journal of sports sciences》2013,31(19):2205-2212

ABSTRACT

This study examined the reliability and validity of three methods of estimating the one-repetition maximum (1RM) during the free-weight prone bench pull exercise. Twenty-six men (22 rowers and four weightlifters) performed an incremental loading test until reaching their 1RM, followed by a set of repetitions-to-failure. Eighteen participants were re-tested to conduct the reliability analysis. The 1RM was estimated through the lifts-to-failure equations proposed by Lombardi and O’Connor, general load-velocity (L-V) relationships proposed by Sánchez-Medina and Loturco and the individual L-V relationships modelled using four (multiple-point method) or only two loads (two-point method). The direct method provided the highest reliability (coefficient of variation [CV] = 2.45% and intraclass correlation coefficient [ICC] = 0.97), followed by the Lombardi’s equation (CV = 3.44% and ICC = 0.94), and no meaningful differences were observed between the remaining methods (CV range = 4.95–6.89% and ICC range = 0.81–0.91). The lifts-to-failure equations overestimated the 1RM (3.43–4.08%), the general L-V relationship proposed by Sánchez-Medina underestimated the 1RM (?3.77%), and no significant differences were observed for the remaining prediction methods (?0.40–0.86%). The individual L-V relationship could be recommended as the most accurate method for predicting the 1RM during the free-weight prone bench pull exercise.  相似文献   

‘Strong mothers make strong children’: sports,eugenics and nationalism in Brazil at the beginning of the twentieth century     

Silvana Vilodre Goellner  Sebastião Josué Votre  Maria Claudia Brandão Pinheiro 《Sport, Education and Society》2013,18(4):555-570

Based on post-structural feminist and gender studies, the present article analyses the importance given to the practice of physical education, sports and exercise as part of the national policy to strengthen the Caucasian-Brazilian population at the beginning of the twentieth century, emphasising the priority made of the White female body as the most important instrument in strengthening the so called ‘White race’. All the editions of the Revista Educação Physica, the first magazine published specifically for physical education and sport in Brazil, was the primary research source. Other books, manuals, reviews from scientific congresses and official publications from the Brazilian Government at the time were also examined. Via the technical analysis of the contents of the aforementioned publications, it was possible to conclude that the Brazilian nationalist discourse at the time sought what was called the ‘refinement of the White race’ by strengthening its women while, at the same time, systematically ignoring Black women.  相似文献   

Is passive drag dependent on the interaction of kayak design and paddler weight in flat-water kayaking?     

Beatriz B. Gomes  Filipe A.V. Conceição  David R. Pendergast  Ross H. Sanders  Mário A.P. Vaz  João Paulo Vilas-Boas 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):394-403

Abstract

Drag is one of the major factors that influences kayaking performance. To focus on the drag of the kayak’s hull shape and the paddlers’ weight per se, the passive drag (D_p) was measured on a flat-water sprint course for one paddler with added weights. D_p was measured by an electromechanical towing device using a load cell, at incremental and constant velocities from 2.78 to 5.56 m/s. Three kayaks of different sizes and shapes (Nelo® K1 Quattro-M, ML, and L) were used and the paddlers’ body weight was adjusted with weights so the total paddler weight in the kayak was 65, 75, and 85 kg. The mean D_p increased by the power function of D = kvⁿ (mean R² = .990; SD .006). The D_p went from 21.37?±?1.29 N at 2.78 m/s to 89.32?±?6.43 N at 5.56 m/s. For the two lighter weighted kayaks (65 and 75 kg), the lowest D_p was observed with different kayak sizes (M, ML, or L) depending on the target velocity. The manufacturers suggest that paddlers should select a kayak size according to their body weight to minimise drag; however, the results of this study suggest that target velocities, and thus competition distance should also be factored into kayak selection.  相似文献   

Inverted classroom teaching in the first-year design studio,a case study     

Maria Elisa Navarro Morales  Roberto Londoño 《British journal of educational technology : journal of the Council for Educational Technology》2019,50(5):2651-2666

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Approaches to Teacher Professional Development: a critical appraisal*     

João M. Moreira 《欧洲师范教育杂志》1996,19(1):47-63

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A developmental perspective on full- versus part-day kindergarten and children's academic trajectories through fifth grade   总被引：1，自引：0，他引：1  

Votruba-Drzal E  Li-Grining CP  Maldonado-Carreño C 《Child development》2008,79(4):957-978

Children's kindergarten experiences are increasingly taking place in full- versus part-day programs, yet important questions remain about whether there are significant and meaningful benefits to full-day kindergarten. Using the Early Childhood Longitudinal Study's Kindergarten Cohort ( N = 13,776), this study takes a developmental approach to examining associations between kindergarten program type and academic trajectories from kindergarten (ages 4–6 years) through 5th grade (ages 9–12 years). Full-day kindergarten was associated with greater growth of reading and math skills from fall until spring of kindergarten. Initial academic benefits diminished soon after kindergarten. The fade-out of the full-day advantage is in part explained by differences in the children who attend part- and full-day kindergarten as well as school characteristics.  相似文献   

Adding automatic evaluation to interactive virtual labs     

Gonzalo Farias  David Muñoz de la Peña  Fabio Gómez-Estern  Luis De la Torre  Carlos Sánchez  Sebastián Dormido 《Interactive Learning Environments》2016,24(7):1456-1476

Automatic evaluation is a challenging field that has been addressed by the academic community in order to reduce the assessment workload. In this work we present a new element for the authoring tool Easy Java Simulations (EJS). This element, which is named automatic evaluation element (AEE), provides automatic evaluation to virtual and remote laboratories built with EJS by using the server application Goodle grading management system (GMS). The integration of both tools entitles a professor to create interactive virtual and remote laboratories and automatically evaluate the work of their students. As a test bed two case studies are presented; a non-linear controller design virtual laboratory used in an advanced control master course and a servomechanism virtual laboratory used in an undergraduate basic control course.  相似文献   

Hybrid Deterministic Views About Genes in Biology Textbooks: A Key Problem in Genetics Teaching     

Vanessa Carvalho dos Santos  Leyla Mariane Joaquim  Charbel Ni?o El-Hani 《Science & Education》2012,21(4):543-578

A major source of difficulties in promoting students’ understanding of genetics lies in the presentation of gene concepts and models in an inconsistent and largely ahistorical manner, merely amalgamated in hybrid views, as if they constituted linear developments, instead of being built for different purposes and employed in specific contexts. In this paper, we report the results of a study about how textbooks can provide the grounds for the students’ construction of such hybrid views about genes. These views are a key problem in genetics teaching, because they make it more difficult that students properly understand this central biological concept and strengthen genetic deterministic ideas, which characterize a widespread discourse about genes in the public opinion. We analyzed 18 textbooks using categorical content analysis, employing categories derived from the literature addressing the historical development of gene models and concepts. Our findings indicate that the analyzed textbooks do convey hybrid views about genes, with no correspondence to scientific models related to this biological concept. These views reinforce genetic deterministic discourses and may lead students to serious misunderstandings about the nature of genes and their role in living systems, with consequences to future learning about genetics.  相似文献